In addition to the main qflow distribution download, you
will need to obtain a number of other tools for the digital
standard cell tool chain. The preferred toolchain includes
the yosys synthesis tool. Note that yosys
will automatically download and compile a version of the
logic optimization tool abc.

NOTE:
This patch file is required for versions of graywolf prior
to the git update on May 25, 2015, if used with qflow version 1.1.
Generally, however, it is recommended to simply update graywolf
from the git repository.

If you decide to download and apply the patch anyway, put the patch
file in the graywolf source directory, and do

An alternative toolflow for qflow-1.0 uses the Odin-II
synthesis tool.
This toolchain was developed before yosys was available
and has been kept around more for historic reasons than anything
else. Its capabilities are limited compared to yosys, and
there are additional complications to the compile and install
process. Qflow version 1.1 had abandoned this code as being
too difficult to support and far inferior to yosys. It may still
be used with qflow version 1.0.

Note that the link to "Odin-II"
and "abc" is a pointer to the VTR package. Go to the
website, click on the tab "Source", and follow the
instructions for SVN check-out from
there to get the most recent code sources. It is not
necessary to compile the entire VTR distribution, although
you may if you want to. Just make sure that you descend
into the directories "libarchfpga" (a dependency for Odin-II),
"ODIN_II", and "abc_with_bb_support", and run "make" in each
of these subdirectories. That should be enough to compile
everything needed by qflow.

As of September 2013, the updates to Odin-II have not become
part of the official VTR distribution tarball. So you must
use the SVN checkout to get the source that is compatible with
qflow. Here are the instructions on how to get VTR
through SVN, copied from the google code page:

I submitted a patch for Odin-II in October, 2013. As of this writing
(October 11, 2013), it has not been incorporated into the Odin SVN
source code. To prevent Odin-II from crashing when handling multiple
verilog source files for a single project, download the file "odin.patch"
below. Place the file in the Odin source code top level, and apply
the patch by issuing the command "patch -p1 < odin.patch" from the
command line. When this patch has been incorporated into the Odin
SVN repository, I will remove the patch file from this website. For
simple projects having only one module and one verilog source file,
this patch is unnecessary.

The following tools were required by earlier versions of QFlow
(before 1.0), and are no longer used in the synthesis flow.

The vl2mv download
contains the same verilog parser that is found in VIS.
However, this version contains a patch to fix a critical
synthesis error. Note that VIS and vl2mv are no longer
supported; instead, yosys or Odin-II are preferred as far more
capable parsers (especially yosys). The sis download has
a number of minor fixes that may make it easier to compile if you
have a finicky compiler and can't get the version from the
developer's website to work.

As of October 2014, TimberWolf has been added to the set of
deprecated tools.
Ruben Undheim has forked a streamlined version of TimberWolf and
placed it on GitHub under the name "graywolf". This version
has only the sources used by Qflow, has been rewritten to
configure with "cmake", and installs to a standard location (i.e.,
/usr/local/bin/). Qflow is dropping TimberWolf support in favor
of this update.